Hi Andrej,
adding a custom field is 2 ways this will not store the data in your standard table this will give the data at run time...
1 under any context node attribute right click create attribute select value node or model node.
2 identify the base entity name and add append structure then go to config move the field to available to display.
where as if you add a field using AET the field which you added that will store the data into there corresponding table as well as when ever you have pass the value into that field in web ui that will be store the data into that tables.
now you have to say in which method you want to choose..
Thanks & Regards,
Srinivas